With development of short range communications technologies, there are an increasing number of anti-lost target devices based on the short range communications technologies. Commonly used short range communications technologies include a Bluetooth® with low energy (BLE) technology and a Wireless Fidelity (WI-FI) technology. The anti-lost target device is, for example, a tracking label, a child anti-lost wristband, or a wrist watch. The anti-lost target device may be an independent device, and may be carried on an anti-lost object. The anti-lost object may be a person or another object. The anti-lost target device has a short range communications function, and can establish a short range communications connection to a mobile terminal carried by a user. When a distance between the anti-lost target device and the mobile terminal exceeds a particular threshold, strength of a wireless signal of the short range communications connection established between the anti-lost target device and the mobile terminal weakens, and the mobile terminal or the anti-lost target device sends a prompt warning, for example, notifies, by means of a sound, the user that the anti-lost target device is moving away from the user. After hearing the warning, the user finds that the anti-lost target device is moving away from the user, and attempts to look for the anti-lost target device.
In the prior art, a wireless signal attenuation characteristic is used to determine a distance between a user and an anti-lost object by using a change of strength of a wireless signal between an anti-lost target device and a mobile terminal. When the mobile terminal is moving away from the anti-lost target device, strength of a signal received by the mobile terminal weakens. When the mobile terminal approaches the anti-lost target device, the strength of the signal received by the mobile terminal is enhanced. In the prior art, relying on signal strength of a wireless signal, only a distance between the anti-lost target device and the mobile terminal can be determined, but a specific location of the anti-lost target device cannot be determined, thereby bringing particular uncertainty and blindness to searching for the anti-lost target device by the user.